Improve error diagnostics.

src/pio_posixnonb.c

@@ -213,7 +213,7 @@ pioWriterStdIO(void)
           {
             int buffer, collID;
 
-            xmpi(MPI_Recv(&buffer, 1, MPI_INT, source, tag, commPio, &status));
+            xmpiStat(MPI_Recv(&buffer, 1, MPI_INT, source, tag, commPio, &status), &status);
 
             sentFinalize[source] = true;
             doFinalize = true;